Liquid crystal display panel

ABSTRACT

A liquid crystal display panel including an active device array substrate, an opposite substrate, a plurality of patterned electrodes, and a liquid crystal layer is provided. The active device array substrate includes a substrate, a plurality of scan lines, a plurality of data lines, and a plurality of pixel units. The substrate mentioned has a plurality of shots. The scan lines, data lines, and pixel units are all disposed on the substrate. Additionally, the opposite substrate is disposed above the active device array substrate, and the plurality of patterned electrodes is disposed on the opposite substrate. The liquid crystal layer is disposed between the patterned electrodes and the active device array substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 95124281, filed on Jul. 4, 2006. All disclosure of the Taiwanapplication is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a display apparatus. More particularly,the present invention relates to a liquid crystal display panel capableof improving display quality.

2. Description of Related Art

Due to the progress of semiconductor devices or display apparatuses,current multimedia technology is well developed. Among displays, thinfilm transistor liquid crystal displays (TFT LCD) characterized in highpicture quality, good space utilization, low power consumption, and noradiation etc. have gradually become mainstream products in the market.

An common TFT LCD is mainly constituted of a TFT array substrate, acolor filter substrate, and a liquid crystal layer sandwiched betweenthe above two substrates. The TFT array substrate has a plurality ofpixel electrodes disposed thereon, the color filter substrate has acommon electrode layer disposed thereon, and the liquid crystal layer iscontrolled by the electric field between the pixel electrodes and thecommon electrode layer. The TFT array substrate is mainly formed by amask process. For example, in the conventional five mask processes, thefirst mask process mainly defines the gate and scan line; the secondmask process mainly defines the channel layer; the third mask processmainly defines the source, drain, and data line; the fourth mask processmainly defines the passivation layer; and the fifth mask process mainlydefines the pixel electrode.

However, currently, the exposure method adopted in a mask process ismainly achieved by the use of a stepper or scanner. Referring to FIG. 1,as for a stepper, when the dimension of the mask is smaller than asubstrate 110, the substrate 110 must be divided into a plurality ofshots 10 for performing several exposures to complete exposing theentire region required on the substrate 110. For example, a 12-inch or14-inch substrate must be exposed four times, and a 15-inch or 17-inchsubstrate 110 must be exposed six times. It should be noted that themore the shot 10 is, the easier the alignment offset between the shots10 occurs. Therefore, the film layers formed at different positions inthe shots 10 may have offset to some extent.

FIG. 2 is a partial schematic view of the pixel structure on aconventional TFT array substrate. Referring to FIG. 2, a conventionalpixel structure 100 mainly comprises a TFT 122, a pixel electrode 124, ascan line 126, and a data line 128. The pixel electrode 124 iselectrically connected to the corresponding scan line 126 and data line128 through the TFT 122. It should be noted that a region 20 overlappedby a gate 122 g and a drain 122 d together with a region 30 overlappedby the pixel electrode 124 and the scan line 126 generates a gate-drainparasitic capacitance C_(gd) effect, and the value of the gate-drainparasitic capacitance C_(gd) is in direct proportion to the area of theregions 20, 30.

Generally, when fabricating the TFT, due to factors such as errors inthe alignment of the mask or vibration, the area of the regions 20, 30respectively overlapped by the gate 122 g and drain 122 d changes. As aresult, the value of the gate-drain parasitic capacitance C_(gd) variesin the shots 10 at different positions. However, the value of thegate-drain parasitic capacitance C_(gd) may directly affect the pixelfeedback voltage used for driving the liquid crystal molecules. If thedifference between the pixel feedback voltages in shots 10 at differentpositions is too great, a problem of shot mura may occur to the displayframe of the TFT LCD at the edges of the shots.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide a liquid crystaldisplay panel, so as to solve the problem of shot mura due to shots inthe conventional TFT LCD.

In order to fulfill the above or other objectives, the present inventionprovides a liquid crystal display panel, which comprises an activedevice array substrate, an opposite substrate, a patterned electrode,and a liquid crystal layer. The active device array substrate comprisesa substrate, a plurality of scan lines, a plurality of data lines, and aplurality of pixel units. The substrate has a plurality of shots. Thescan lines and data lines are disposed on the substrate. Additionally,the pixel units are arranged on the substrate in arrays. The oppositesubstrate is disposed above the active device array substrate, theplurality of patterned electrodes is respectively disposed on theopposite substrate, and the juncture of at least a portion of the shotscorresponds to the juncture of the patterned electrodes. The liquidcrystal layer is disposed between the patterned electrodes and theactive device array substrate.

In an embodiment of the present invention, the patterned electrodes arerespectively connected to different reference voltages.

In an embodiment of the present invention, the liquid crystal displaypanel further comprises a plurality of conductive paste dots disposed onthe side edges of the patterned electrodes, and the patterned electrodesare electrically connected to the external circuit via the conductivepaste dots.

In an embodiment of the present invention, the material of theconductive paste dot comprises silver paste or carbon paste.

In an embodiment of the present invention, the pixel unit comprises atleast one active device and a pixel electrode, wherein the pixelelectrode is electrically connected to the corresponding scan line anddata line via the active device.

In an embodiment of the present invention, the opposite substratefurther comprises a base, a black matrix, and a plurality of colorfilter thin films. The black matrix is disposed on the base and has aplurality of lattice points. The color filter thin films are disposed onthe base and respectively in the lattice points.

In an embodiment of the present invention, the material of the colorfilter thin film comprises red, blue or green resins.

In an embodiment of the present invention, the opposite substrate is atransparent substrate.

In an embodiment of the present invention, if the opposite substrate isa transparent substrate, the liquid crystal display panel furthercomprises a color filter disposed on the active device array substrate,and the liquid crystal layer is disposed between the color filter andthe opposite substrate.

In an embodiment of the present invention, the material of the patternedelectrode comprises indium tin oxide (ITO), indium zinc oxide (IZO), oraluminum zinc oxide (AZO).

In an embodiment of the present invention, the liquid crystal displaypanel further comprises a buffer film layer disposed between two shots.

In an embodiment of the present invention, the material of the bufferfilm layer comprises N-type doped amorphous silicon.

The opposite substrate of the present invention has a plurality ofpatterned electrodes disposed thereon, and the patterned electrodes areconnected to different reference voltages. Thus, the voltage differencegenerated between the pixel electrodes on the active device arraysubstrate and the patterned electrodes can be made consistent byadjusting the reference voltages to which the patterned electrodes areconnected. As such, the phenomenon of great difference between the pixelfeedback voltages resulting from the alignment offset caused by exposureof the pixel electrodes can be avoided, thereby providing a good displayquality of the liquid crystal display panel.

In order to make the aforementioned and other objectives, features andadvantages of the present invention comprehensible, preferredembodiments accompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the shots on the substrate in theconventional art.

FIG. 2 is a partial schematic view of the pixel structure on the TFTarray substrate in the conventional art.

FIG. 3 is a schematic view of the liquid crystal display panel accordingto the present invention.

FIG. 4A is a schematic view of the active device array substrateaccording to the present invention.

FIG. 4B is a schematic view of the opposite substrate according to thepresent invention.

FIG. 5 is a schematic sectional view of the opposite substrate accordingto the present invention.

FIG. 6 is another liquid crystal display panel according to the presentinvention.

FIG. 7 is a schematic view of the relative position between the shotsand the patterned electrodes according to the present invention.

FIG. 8A is a schematic view of the buffer film layer and the opticaleffect thereof according to the present invention.

FIG. 8B is a schematic view of the optical effect of the liquid crystaldisplay panel without the buffer film layer according to the presentinvention.

DESCRIPTION OF EMBODIMENTS

FIG. 3 is a schematic view of the liquid crystal display panel accordingto the present invention. Referring to FIG. 3, a liquid crystal displaypanel 200 of the present invention comprises an active device arraysubstrate 210, an opposite substrate 220, and a liquid crystal layer230, wherein the liquid crystal layer 230 is disposed between the activedevice array substrate 210 and the opposite substrate 220. Inparticular, the arrangement state of the liquid crystal molecules in theliquid crystal layer 230 is mainly controlled by the pixel feedbackvoltage generated between the active device array substrate 210 and theopposite substrate 220.

FIG. 4A is a schematic view of the active device array substrateaccording to the present invention. FIG. 4B is a schematic view of theopposite substrate according to the present invention. Referring toFIGS. 4A and 4B, the active device array substrate 210 of the presentinvention comprises a substrate 212, a plurality of scan lines 214, aplurality of data lines 216, and a plurality of pixel units 218, whereinthe substrate 212 has a plurality of shots A, B, C, and D disposedthereon. It should be noted that the number of the shots A, B, C, and Ddepends on the dimension of the substrate 212 and the dimension of themask used in the lithography process. Only four shots A, B, C, and D areshown in FIG. 4A for illustration, and the number thereof is notparticularly limited herein.

As shown in FIG. 4A, the pixel units 218 are arranged on the substrate212 in arrays, and the scan lines 214 and data lines 216 mark out thepositions of the pixel units 218. Generally speaking, each of the pixelunits 218 has at least one active device T and a pixel electrode P1,depending on the design of the performance of the pixel units 218. Forexample, the pixel unit 218 having the design of pre-charge performanceneeds more than two active devices T, wherein the number of the activedevice T in each pixel unit 218 is not particularly limited herein. Inaddition, the pixel electrode P1 can be made of ITO, IZO, or AZO.

The aforementioned active device T is disposed on the substrate 212, andthe pixel electrode P1 is electrically connected to the correspondingscan line 214 and data line 216 through the active device T. Inparticular, a switch signal transmitted through the scan line 214 turnson the active device T. After the active device T is turned on, adisplay signal is transmitted into the pixel electrode P1 through thedata line 216, thereby generating the pixel feedback voltage togetherwith the electrode (described in detail hereinafter) on the oppositesubstrate 220.

It should be stressed that, the opposite substrate 220 may have aplurality of patterned electrodes P2 disposed thereon. Though only twopatterned electrodes P2 are shown in FIG. 4B, the number of thepatterned electrode P2 is not particularly limited herein as long asbeing more than one. The material of the patterned electrodes P2 can beITO, IZO, or AZO. The patterned electrodes P2 are respectively disposedon the opposite substrate 220 and are electrically insulated from eachother. Further, the juncture of the shots A, B, C, and D corresponds tothe juncture of the patterned electrodes P2.

Referring to FIG. 5, in particular, the opposite substrate 220 can be acolor filter, such that the liquid crystal display panel 200 can achievethe effect of full-color display. The opposite substrate 220 comprises abase 222, a black matrix 224, and a plurality of color filter thin films226. The black matrix 224 and the color filter thin films 226 aredisposed on the base 222, and the black matrix 224 has a plurality oflattice points 224 a. The color filter thin films 226 are respectivelydisposed in the lattice points 224 a. Generally speaking, the materialof the color filter thin films 226 can be red, blue, or green resins.Further, the black matrix 224 can be made of Cr, black resin orfabricated by stacking red, blue, and green resins.

Definitely, the opposite substrate 220 can also be a transparentsubstrate (as shown in FIG. 6). At this time, a color filter on array(COA) technique can be applied to the active device array substrate 210,wherein the COA technique refers to forming a color filter 221 on theactive device array substrate 210 and respectively disposing thepatterned electrodes P2 on the opposite substrate 220. That is, theliquid crystal layer 230 is disposed between the color filter 221 andthe opposite substrate 220.

It should be particularly noted that after being charged, the pixelelectrode P1 and the patterned electrodes P2 generate the pixel feedbackvoltage, thereby driving the liquid crystal molecules. However, it isvery likely that the devices formed in different shots A, B, C, and D onthe substrate 212 have different electrical properties due to thealignment offset or vibration during the lithography process. As aresult, after the pixel electrodes P1 in the shots A, B, C, and D arecharged, the quantities of the electric charges are different.

In order to effectively keep the consistency of the pixel feedbackvoltages, the patterned electrodes P2 can be selectively connected todifferent reference voltages respectively, so as to maintain the voltagedifference generated between the patterned electrodes P2 and the pixelelectrodes P1. As such, even if the quantities of the electric chargesof the pixel electrodes P1 are different after being charged, thevoltage difference between the pixel electrodes P1 in different shots A,B, C, D and the patterned electrodes P2 can be made consistent byadjusting the value of the reference voltage. Compared with only onecommon electrode layer disposed on the conventional color filtersubstrate, such that the different shots A, B, C, and D cannot beadjusted, the liquid crystal display panel 200 of the present inventioncan eliminate the mura phenomenon of the display frame by adjusting thereference voltage, so as to effectively improve the display quality.Definitely, if the active device array substrate 210 is of good quality,the patterned electrodes P2 of the present invention can also be coupledto the same voltage level.

In practice, the patterned electrodes P2 can be selectively connected tothe external circuit (not shown), for example, drive chip via aplurality of conductive paste dots R. The drive chip can providedifferent voltages respectively to the patterned electrodes P2, suchthat the voltage difference between the patterned electrodes P2 and thepixel electrodes P1 can be well controlled. The conductive paste dots Rcan be selectively disposed on the side edges of the patternedelectrodes P2 for facilitating the electric connection to the externalcircuit. Generally speaking, the material of the conductive paste dots Rcan be silver paste or carbon paste.

FIG. 7 is a schematic view of the relative position of the shots and thepatterned electrodes according to the present invention. Referring toFIG. 7, the substrate 212 can also have six shots A, B, C, D, E, and Fdisposed thereon. The opposite substrate 220 can have three patternedelectrodes P2 disposed thereon. It should be noted that the juncture ofthe patterned electrodes P2 corresponds to the juncture of the shots A,B, C, D, E, and F.

FIG. 8A is a schematic view of the buffer film layer and the opticaleffect thereof according to the present invention. FIG. 8B is aschematic view of the optical effect of the liquid crystal display panelwithout the buffer film layer according to the present invention.Referring to FIGS. 8A and 8B, in order to make the liquid crystaldisplay panel 200 have a better display quality, the liquid crystaldisplay panel 200 of the present invention further comprise a bufferfilm layer H, and the buffer film layer H is disposed between any twoadjacent shots of A, B, C and D.

For example, if the buffer film layer H is disposed between the shots Aand C, the buffer film layer H can effectively prevent a large drop ofthe overall energy (as shown in FIG. 8A), thereby further enhancing thedisplay effect. On the contrary, if there is no buffer film layer H, thejuncture between the shots A and C may have apparent energy drop (asshown in FIG. 8B). In particular, the total width of the buffer filmlayer H is, for example, 5 mm, which can be appropriately adjusted asrequired. Moreover, the material of the buffer film layer H can beN-type doped amorphous silicon. In practice, the buffer film layer H canbe selectively fabricated together with the channel layer. Definitely,the buffer film layer H can also be made by other suitable materials,and it is not intended to be limited herein.

In view of the above, as the opposite substrate of the present inventionhas a plurality of patterned electrodes disposed thereon and thepatterned electrodes can be selectively connected to different referencevoltages to adjust the voltage differences generated between thepatterned electrodes and the pixel electrode. Therefore, even if thequantity of the electric charges of the pixel electrode is differentafter being charged, the voltage difference between the pixel electrodesin different shots and the patterned electrodes can be made consistentby adjusting the value of the reference voltage, thereby effectivelycontrolling the liquid crystal molecules. As such, the liquid crystaldisplay panel of the present invention can effectively eliminate themura phenomenon of the display frame, thereby enhancing the displayquality.

Though the present invention has been disclosed above by the preferredembodiments, they are not intended to limit the present invention.Anybody skilled in the art can make some modifications and variationswithout departing from the spirit and scope of the present invention.Therefore, the protecting range of the present invention falls in theappended claims.

1. A liquid crystal display panel, comprising: an active device arraysubstrate, comprising: a substrate, having a plurality of shots; aplurality of scan lines, disposed on the substrate; a plurality of datalines, disposed on the substrate; a plurality of pixel units, arrangedon the substrate in an array; an opposite substrate, disposed above theactive device array substrate; a plurality of patterned electrodes,respectively disposed on the opposite substrate, wherein the juncture ofat least a portion of the shots corresponds to the juncture of thepatterned electrodes; and a liquid crystal layer, disposed between thepatterned electrodes and the active device array substrate.
 2. Theliquid crystal display panel as claimed in claim 1, wherein thepatterned electrodes are respectively connected to different referencevoltages.
 3. The liquid crystal display panel as claimed in claim 2,further comprising a plurality of conductive paste dots, disposed on theside edges of the patterned electrodes, wherein the patterned electrodesare electrically connected to an external circuit via the conductivepaste dots.
 4. The liquid crystal display panel as claimed in claim 3,wherein the material of the conductive paste dots is silver paste orcarbon paste.
 5. The liquid crystal display panel as claimed in claim 1,wherein each of the pixel units comprises at least one active device anda pixel electrode, and the pixel electrode is electrically connected tothe corresponding scan line and corresponding data line via the activedevice.
 6. The liquid crystal display panel as claimed in claim 1,wherein the opposite substrate further comprises: a base; a blackmatrix, disposed on the base, wherein the black matrix has a pluralityof lattice points; and a plurality of color filter thin films, disposedon the base and respectively in the lattice points.
 7. The liquidcrystal display panel as claimed in claim 6, wherein the material of thecolor filter thin films comprises red, blue or green resins.
 8. Theliquid crystal display panel as claimed in claim 1, wherein the oppositesubstrate is a transparent substrate.
 9. The liquid crystal displaypanel as claimed in claim 8, further comprising a color filter, disposedon the active device array substrate, wherein the liquid crystal layeris disposed between the color filter and the opposite substrate.
 10. Theliquid crystal display panel as claimed in claim 1, wherein the materialof the patterned electrodes comprises indium tin oxide (ITO), indiumzinc oxide (IZO), or aluminum zinc oxide (AZO).
 11. The liquid crystaldisplay panel as claimed in claim 1, further comprising a buffer filmlayer disposed between two shots.
 12. The liquid crystal display panelas claimed in claim 11, wherein the material of the buffer film layercomprises N-type doped amorphous silicon.